Vertically integrated asphalt plant

ABSTRACT

An asphalt plant comprising a vertically upwardly extending support framework, a heated storage hopper or tank supported on the framework, and an asphalt mixing system supported on the framework above the upper end of the heated storage hopper. The mixing system includes a mixer, commonly called a pug mill, for hot liquid asphalt and sand and stone, a weigh hopper positioned above the mixer and arranged to deposit controlled amounts of sand and stone into the mixer, and a second storage hopper for sand and stone mounted on the framework above the weigh hopper. A pumping system is provided for pumping hot liquid asphalt upwardly to the mixer. A conveyor is provided for conveying dried and heated sand and stone upwardly to the second storage hopper.

[451 Feb. 18, 1975" l VERTICALLY INTEGRATED ASPHALT PLANT [75] Inventor: Howard E. Potter, Bedford, Ind.

[73] Assignee: Oolitic Ground Limestone Co., Inc.,

Bedford, 1ndv [22] Filed: Dec. 13, 1973 [21] Appl. No.: 424,446

[52] US. Cl 259/154, 222/146 H, 259/161,

259/165 [51] Int. Cl. B28c 1/22 [58] Field of Search 259/154, 155, 156, 157,

259/158,159 R, 159 A,160,161,162,164, 165, 169, 149; 222/146 R, 146 H 9/1971 Sackett 259/154 3,625,488 12/1971 Farnham 259/159 R R26,786 2/1970 Plumb 259/151 Primary Examiner-Robert W, Jenkins Attorney, Agent, or FirmWilliam R. Coffey [57] ABSTRACT An asphalt plant comprising a vertically upwardly extending support framework, a heated storage hopper or tank supported on the framework, and an asphalt mixing system supported on the framework above the upper end of the heated storage hopper. The mixing system includes a mixer, commonly called a pug mill, for hot liquid asphalt and sand and stone, a weigh hopper positioned above the mixer and arranged to deposit controlled amounts of sand and stone into the mixer, and a second storage hopper for sand and stone mounted on the framework above the weigh hopper. A pumping system is provided for pumping hot liquid asphalt upwardly to the mixer. A conveyor is provided for conveying dried and heated sand and stone upwardly to the second storage hopper.

8 Claims, 2 Drawing Figures PATENTEU F551 81975 1866,88?

SAND 8 STONE DRYER IOO Fig.1 8'

VERTICALLY INTEGRATED ASPHALT PLANT The present invention relates to asphalt plants, and more particularly to the provision of a vertically integrated asphalt plant comprising a heated storage or holding tank of a size sufficient to contain several truck loads of heated asphalt mix, the tank being supported at a height sufficient to accommodate conventional trucks thereunder to be loaded with the asphalt mix. The asphalt plant of the present invention is vertically integrated in that the mixing system, including the storage hopper for heated and dried sand and stone, weigh hopper, and pug mill for mixing the sand and stone with heated liquid asphalt are all mounted above the upper end ofthe large heated storage hopper. The heated and dried sand and stone are conveyed from ground level vertically upwardly to a storage hopper, from which the sand and stone drop into the weigh hopper. The weigh hopper drops the sand and stone, in controlled amounts, into the pug mill where the sand and stone are well mixed with hot liquid asphalt which is pumped upwardly from ground level into the pug mill. 2

The system of the present invention is in contrast to the prior art systems which include an asphalt mixing system at ground level and a storage hopper for loading trucks, the hot mixed asphalt being delivered from the mixing system upwardly to the upper end of the storage hopper by conveyor means, usually a skip hoist, In other words, prior art systems have been constructed such that batches of asphalt are mixed and then deposited into a conveyor, such as a skip hoist, for transfer to a holding or storage tank which is heated and which will contain several truck loads of asphalt mix. U.S. Pats. Nos. 2,112,326 (Cl. 94-41); 3,378,171 (Cl. 222-146); 3,484,083 (Cl. 259-155); 3,554,498 (Cl. 259-159-164); 3,603,567 (Cl. 259-4, 259-154, 259-180); 3,625,488 (Cl. 259-154, 259-159); and Re.26,786 (Cl. 259-151) are known to applicant to be patents showing prior art systems. The Eaton US. Pat. No. 3,378,171, for instance, shows an asphalt plant or mixer for producing asphalt mix, a large multi-load heated storage hopper, and a heated elevator for conveying the heated and mixed asphalt from the mixer to the upper end of the storage hopper.

Persons involved with and knowledgeable about asphalt are well aware that a hot asphalt mix presents complicated and distressing material handling problems. Conveyors, such as skip hoists, are failure prone when subjected to the task of conveying a hot asphalt mix. The asphalt material clogs up the bearings, guides, ways and the like to the point that the conveyor generally is failure prone.

It is much easier, of course, to convey a heated and dried mixture of sand and stone than to convey a heated mixture of sand and stone and asphalt liquid. In the present invention, the heated and dried mixture of sand and stone is conveyed to the very top of the asphalt plant or mixing system which is disposed above the multi-load heated storage hopper. Then, hot liquid asphalt is pumped upwardly to the mixing means or pug mill which is disposed above the upper end of the heated storage tank. Thus, in the plant of the present invention, once the hot liquid asphalt is mixed with sand and stone, it is merely dropped from the pug mill into the heated storage tank capable of holding several truck loads. The heated storage tank is supported at a height such that the trucks can park thereunder to be loaded. Of course, the storage tank is provided with a loading gate at its lower end for purposes of loading the trucks.

An important object of the present invention, therefore, is to eliminate the necessity for conveying hot asphalt mix from the mixer to the heated storage tank.

Another object of the present invention is to provide an asphalt plant which is highly compact and which does not require an inordinate amount ofland space for its erection. The prior art systems are such that the mixing plants occupy space and then the holding tank or heated storage tank itself occupies a separate and significant amount of space.

Since the cost of the supporting steel framework for equipment such as hoppers, conveyors and the like is a major portion of the total cost of a complete system, the system of the present invention is economical in that the same steel framework which supports the heated storage tank also supports the pug mill mixer, weigh hopper and storage hopper for the heated and dried sand and stone.

Still another object of the present invention is to provide a system which will prevent or at least significantly reduce the segregation of the components of the asphalt mix. This is true because the finished material, i.e., the hot mixed asphalt, is only handled or moved one time before loading into trucks. This is in contrast to the aforementioned skip hoist system which moves small batches of hot mixed asphalt up to the top of the storage tank. Any movement of the hot mixed asphalt causes segregation. Additionally, any movement causes loss of heat. The movement of small batches in a skip hoist causes excessive loss of heat. Further, each time a small batch is moved in a skip hoist bucket, a layer of asphalt mix is applied to the interior of the bucket. After a while, the system must be shut down so that the buckets can be cleaned out.

In the system of the present invention, precautions are taken to prevent heat loss. The storage tank is preferably heated and covered with insulation except for the inlet port. The inlet port is covered by the mixer.

Other objects and features of the present invention will become apparent as this description progresses.

To the accomplishment of the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described, so long as the scope of the appended claims is not violated.

In the drawings:

FIGS. 1 and 2 are side and front elevation views, respectively, of the asphalt plant of the present invention.

Referring now to the drawings, it will be seen that there is illustrated a plant 10 comprising a generally vertically upwardly extending support framework, indicated generally at 12, a major portion of which is defined by four heavy steel corner posts, three of which are identified in the drawings by reference numerals l4, l6, 18. Each corner post has an upper end 20, a lower portion 26, intermediate portion 28, and upper portion 30. The lower and upper portions are vertically extending while the intermediate portions 28, as best seen in FIG. 2, incline rearwardly and forwardly, respectively.

The framework 12 provides a first platform or support frame 38 at a first height, this platform being provided primarily by horizontally extending crossmembers 40 extending between the corner posts. Accessory equipment, such as air compressors, may be mounted on the platform 38. The framework 12 also provides a second platform or support frame 46 at a second and greater height, this second platform being supported primarily on crossmembers 48. Another set of corner posts 52 extend upwardly from the platform 46 to support a third platform or support frame 54 at a third and still greater height and upon which a sand and stone hopper 56 is supported. The hopper 56, which is the second hopper of the present invention, is supported and positioned by a frame including frame members 58.

Means for mixing heated and dried sand and stone with hot liquid asphalt is provided and mounted on the platform 46. The illustrative means includes a conventional and commercially available pug mill 64. A weigh hopper 66 including a scale 68 is mounted upon the pug mill 64 deposit controlled amounts of the sand and stone mixture into the pug mill. That is, sand and stone are deposited from the hopper 56 into the weigh hopper and from the weigh hopper into the pug mill. The hopper 56 is not heated in the illustrative embodiment and l presently believe that it is not necessary to heat the hopper 56 or to insulate it to any significant extent. Within the scope of my present invention, however, it may be both heated and insulated.

The mixed sand, stone and liquid asphalt is dropped from the pug mill 64 through a walled space indicated at 72 into a large, heated storage hopper 74 supported on the framework 12 and extending generally between the first and second platforms 38, 46. The walled space 72 may preferably be provided by four panels hinged at their lower edges for swinging movement from their lower positions against the top of the hopper 74 to their vertical positions defining a vertically extending, rectangular space. The top of the hopper 74, except for the opening through which the mix drops, is covered with insulative means, The illustrative hopper 74 is cylindrical at the top and conically shaped at the bottom, the

conical portion coinciding with the intermediate portions 28 of the corner posts of the support frame. Supported at and by the lower portion of the hopper 74 is a loading gate 76 of conventional and commercially available type. Conventional asphalt trucks may be parked under the loading gate in the space indicated at 78 to be loaded from the hopper 74. The hopper 74 may be, for instance, of a size sufficient to hold 75 tons of hot asphalt mix, i.e., several truck loads of hot asphalt mix. While the accompanying drawings should not be scaled, they are generally proportional to the actual system which has been constructed. The loading gate in that system is at a height of approximately feet while the top of the hopper 74 is at a height of approximately 30 feet. The platform 46 is at a height of approximately 33 feet. The hopper 74 has an outer diameter of approximately 12 feet. The mixing system including the hopper 56, weigh hopper 66 and pug mill 64 are, therefore, at a substantial height in the plant of the present invention. The height of the platform 54, for instance, may be approximately 8 feet above the platform 46 while the top of the hopper 56 may be at a height such as 6% feet above the platform 54.

In the illustrative embodiment, the outer cylindrical wall of the hopper 74 is welded as at 79 to the upper portions 30 of the corner posts. An upper support ring 80 and a lower support ring 81 extend about the cylindrical portion of the hopper and are welded to the hopper and the corner posts. These rings 80, 81 may preferably be heavy and strong steel rings for structural purposes.

In order to clean out the hopper 56, a cleanout pipe 84 extending rearwardly and downwardly and outwardly is provided. A pipe 86 is provided for conveying the overflow from the hopper 56 to the cleanout pipe 84. A power gate 90 is provided for opening the cleanout pipe 84 to the hopper 56. The cleanout pipe 84 and power gate 90 may be used to unload the hopper 56 if it is desired to do so, for instance, to shut down operation of the plant 10. Then, in starting up the plant, fresh heated and dried sand and stone can be elevated to the hopper 56.

The framework 12 also includes an assortment of structural members extending between the corner posts as indicated at 94. These structural members 94 may be conventionally welded or otherwise fastened to the framework members.

ln the present invention, means is provided for con- -veying hot liquid asphalt vertically upwardly from the ground level to the pug mill 64. In the illustrative embodiment, there is a tank 100 containing the hot liquid asphalt, a pump 102 and a conduit 104 leading upwardly to the pug mill. Preferably, there will be a conventional and commercially available electricallyoperated metering device arranged to meter controlled amounts of hot liquid asphalt into the mixing means. Such a device may be disposed in the conduit 104 adjacent the mixing means. Further, a source of heated and dried sand and stone must be provided. A block diagram showing of a sand and stone drier 106 is connected by a conveyor indicated at 108 to a vertically extending sand and stone conveyor 114 which has a transition stage 116 at its upper extent. The sand and stone is dropped from the transition stage 116 through a chute 118 into the hopper 56. Several different types of sand and stone driers may be used to provide sand and stone for the conveyor 114. Several different types of systems for heating asphalt into a liquid and pumping it upwardly to the pug mill 64 may be'used for the plant of the present invention.

A ladder structure 124 extends upwardly from the platform 46 to the platform 126 at the transition stage 116 of the conveyor 114. Then, to the side of the framework 12 is a vertically extending post 130 about which extends a series of spiral steps 132 leading from the ground level up to the platform 46.

A plant may be constructed in accordance with the present invention at a cost of, for instance, percent of the cost of constructing an old style plant having the same output capacity, i.e., an old style plant which includes a skip hoist or other conveyor for conveying the hot asphalt mix from the separated, low-level mixing system to the upper end of the storage hopper.

Because the mixed hot asphalt is dropped from the pug mill 64 directly into the storage hopper 74 for loading at a subsequent time directly downwardly into a truck, the tendency for segregation of the materials in the hot asphalt mix is significantly reduced or stopped.

While my system has been described in conjunction with a batch-type system mounted above the hopper 74, it will be appreciated that a continuous-type system may well be mounted above the hopper 74 within the scope of the present invention.

1 claim:

1. An asphalt plant comprising a main, vertically extending framework including a first support frame at a first elevation and a second support frame at a second and higher elevation, a heated and insulated storage hopper supported on said framework and extending generally between said first and second support frames, said hopper providing a loading gate approximately at the height of said first support frame, said first support frame being disposed at a height sufficient to accommodatc conventional asphalt trucks thereunder to be loaded from said hopper, said hopper being of a size sufficient to contain several truck loads of heated asphalt mix, a mixing system mounted on said second support frame, said mixing system including means for mixing hot liquid asphalt with sand and stone, means for conveying such hot liquid asphalt upwardly to said mixing means, said mixing means being disposed to drop the hot mixed material downwardly into the upper end of said storage hopper, a weigh hopper disposed above said mixing means and arranged to deposit controlled amounts of sand and stone into said mixing means, a second storage hopper for holding sand and stone disposed above said weigh hopper, and means for coveying sand and stone upwardly to said second hopper.

2. The plant of claim 1 in which said framework provides a third support frame disposed above said second support frame, said second hopper being mounted upon said third frame, said first, second and third support frames being in vertical registry.

3. The plant of claim 1 in which said means for conveying sand and stone upwardly to said second storage hopper includes a vertically extending conveyor, the upper delivery end of which terminates above said second hopper, and a chute for dropping sand and stone from said delivery end downwardly to said second hopper.

4. The plant of claim 1 including a cleanout pipe extending downwardly from the second hopper and gate means for establishing communication between said second hopper and said cleanout pipe, said gate means being effective, when opened, to unload said second hopper through said cleanout pipe 5. An asphalt plant comprising a vertically upwardly extending support framework, a heated storage hopper supported on said framework, said hopper having a lower end and an upper end, said hopper providing a loading gate at its lower end, said framework supporting said hopper at a height sufficient to accommodate a conventional asphalt truck thereunder to be loaded from said loading gate, said hopper being of a size sufficient to contain several truck loads of heated asphalt mix, a mixing system supported on said framework above the upper end of said storage hopper, said mixing system including means for mixing hot liquid asphalt with sand and stone, means for conveying such hot liquid asphalt upwardly to said mixing means, said mixing means being disposed to drop the mixed material downwardly into the upper end of said storage hopper, a second storage hopper mounted on said framework and positioned above said mixing means and arranged to deposit controlled amounts of sand and stone into said mixing means, and means for conveying sand and stone upwardly to said second hopper.

6. The plant of claim 5 including weigh hopper positioned above said mixing means to receive sand and stone from said second hopper and deposit it, in controlled amounts, into said mixing means.

7. The plant of claim 6 in which said means for conveying sand and stone upwardly to said second storage hopper includes a vertically extending conveyor, the upper delivery end of which terminates above said second hopper, and a chute for dropping sand and stone from said delivery end downwardly to said second hopper.

8. The plant of claim 5 including a cleanout pipe extending downwardly from the second hopper and gate means for establishing communication between said second hopper and said cleanout pipe, said gate means being effective, when opened, to unload said second hopper through said cleanout pipe. 

1. An asphalt plant comprising a main, vertically extending framework including a first support frame at a first elevation and a second support frame at a second and higher elevation, a heated and insulated storage hopper supported on said framework and extending generally between said first and second support frames, said hopper providing a loading gate approximately at the height of said first support frame, said first support fRame being disposed at a height sufficient to accommodate conventional asphalt trucks thereunder to be loaded from said hopper, said hopper being of a size sufficient to contain several truck loads of heated asphalt mix, a mixing system mounted on said second support frame, said mixing system including means for mixing hot liquid asphalt with sand and stone, means for conveying such hot liquid asphalt upwardly to said mixing means, said mixing means being disposed to drop the hot mixed material downwardly into the upper end of said storage hopper, a weigh hopper disposed above said mixing means and arranged to deposit controlled amounts of sand and stone into said mixing means, a second storage hopper for holding sand and stone disposed above said weigh hopper, and means for coveying sand and stone upwardly to said second hopper.
 2. The plant of claim 1 in which said framework provides a third support frame disposed above said second support frame, said second hopper being mounted upon said third frame, said first, second and third support frames being in vertical registry.
 3. The plant of claim 1 in which said means for conveying sand and stone upwardly to said second storage hopper includes a vertically extending conveyor, the upper delivery end of which terminates above said second hopper, and a chute for dropping sand and stone from said delivery end downwardly to said second hopper.
 4. The plant of claim 1 including a cleanout pipe extending downwardly from the second hopper and gate means for establishing communication between said second hopper and said cleanout pipe, said gate means being effective, when opened, to unload said second hopper through said cleanout pipe.
 5. An asphalt plant comprising a vertically upwardly extending support framework, a heated storage hopper supported on said framework, said hopper having a lower end and an upper end, said hopper providing a loading gate at its lower end, said framework supporting said hopper at a height sufficient to accommodate a conventional asphalt truck thereunder to be loaded from said loading gate, said hopper being of a size sufficient to contain several truck loads of heated asphalt mix, a mixing system supported on said framework above the upper end of said storage hopper, said mixing system including means for mixing hot liquid asphalt with sand and stone, means for conveying such hot liquid asphalt upwardly to said mixing means, said mixing means being disposed to drop the mixed material downwardly into the upper end of said storage hopper, a second storage hopper mounted on said framework and positioned above said mixing means and arranged to deposit controlled amounts of sand and stone into said mixing means, and means for conveying sand and stone upwardly to said second hopper.
 6. The plant of claim 5 including weigh hopper positioned above said mixing means to receive sand and stone from said second hopper and deposit it, in controlled amounts, into said mixing means.
 7. The plant of claim 6 in which said means for conveying sand and stone upwardly to said second storage hopper includes a vertically extending conveyor, the upper delivery end of which terminates above said second hopper, and a chute for dropping sand and stone from said delivery end downwardly to said second hopper.
 8. The plant of claim 5 including a cleanout pipe extending downwardly from the second hopper and gate means for establishing communication between said second hopper and said cleanout pipe, said gate means being effective, when opened, to unload said second hopper through said cleanout pipe. 